WO 92/10722 discloses a Hall-effect angle sensor which is able to output angle-proportional signals. The angle is acquired by means of a Hall probe which is located in an air gap formed between two semicylindrical or shell-shaped stator halves.
A rotor comprises two disk-type magnets which are magnetized in an alternating direction and are mounted over a return path disk. The rotor is located before the two stator halves in the axial direction. In this case, the magnetization direction of the magnets is perpendicular to the axis of rotation.
The magnetic flux which issues from the north pole of the disk-type magnet is distributed depending on the angular position of the stator halves with respect to the magnet halves before it enters the south pole of the magnet.
If the north/south axis of the magnet is parallel to the air gap, then approximately half of the magnetic flux will flow through each of the two stator halves. Virtually no flux passes through the air gap in this case. The measurement induction tends to zero.
If the north/south axis of the magnet is perpendicular to the air gap, then virtually the entire magnetic flux first of all enters one stator half, crosses the air gap, enters the second stator half and from there the south pole of the magnet. Consequently, the Hall probe records a measurement induction maximum.
Since the magnetic flux takes a path along which, in addition to the measurement air gap, it must also twice traverse the air gap between magnet and stator halves in the axial direction, fluctuations in this air gap, for example in the form of mechanical axial play, produce a great change in the measured value.
Consequently, the invention is based on the object of specifying a magnetic position sensor which is insensitive to displacements in the movable means in a direction other than the measurement direction.